The present invention, a solar concentrator sectional arrangement, consists of a concave reflective boundary and of a first receiver-converter, a general term for varied methods of coverting solar radiation to other useful forms such as heat and electrical energy, emanating outward from the base area of the concavity and of at least a second receiver-converter following outward after the first, the multiple receiver-converters being able to communicate with each other, and, if desired, of additional reflecting means which may be within the concavity and may be within the field-of-sight of the concavity.
U.S. Pat. No. 4,266,858 is a duplicate-in-part forerunner (which has been tested by scale models and shown workable) by Holland of the present invention and differs from it in that the present invention provides for at least a second receiver-converter and for reflecting means, in addition to the reflective concave boundary, within the geometric purview (the field of sight from the base of the concavity) of the concave reflective boundary.
The embodiment presented in this specification appears capable, by using appropriate dimensions, of attaining a greater concentration ratio and or efficiency than obtainable with the referenced inventions.
The efficacy of more than one receiver-converter (strictly heat absorbers in some references) for increasing efficiency of sunlight utilization in related devices has been pointed out by others. The efficacy for the present invention is for an additional, different and more signifigant purpose and result for the present invention as discussed below.
The present invention utilizes the second receiver-converter for an additional, different application and result (to my knowledge new to the literature) of marked importance (and a signifigant objective) for some overall embodiments utilizing the present invention. In the instance of application of the present invention as the cross-section design of an end-to-end tilted, linear trough for the heating of a liquid in the two receiver-converters which run lengthwise in the trough and transport the liquid, the first receiver-converter (in the base of the trough) is the hot tube normally and the second receiver-converter is the "cold" tube. The placement of both the hot and "cold" tubes in the trough more nearly assures (by placing both tubes in the same environment) that both tubes will achieve the same temperature at the same time during an extended absence of sunlight. Such is important because said embodiments depend on passive, natural circulation (with no pumping, no valves, no draining of tubes at night) from a reservoir, down the "cold" tube and back up the hot tube to the reservoir as a result of the liquid in the hot tube being less dense than that in the "cold" tube. In a prolonged absence of sunlight to the trough, it is important that both hot and "cold" tubes attain the same temperature to avoid circulation and thus avoid cooling the reservoir contents. Both tubes enter the reservoir from essentially the same level.
It is quite possible that the hot and "cold" tubes may exchange roles depending on how the additional reflecting means are used and on the dimensions of the tubes.
Note that the first paragraph above does not fix placement of the multiple receiver-converters except that one follows another. Such is intentional, as previous analytical study has shown that placement other than along the longitudinal centerline of the cross section can have the effect of reducing variation in concentration ratio with different angles of incoming radiation.
The inclusion of additional reflectors within the concave reflective boundary and within the geometric sight of the concave boundary can be useful for increasing efficiency, concentration ratios and productivity by intercepting portions of insolation that would otherwise be lost by reflection out of the cavity or would be intercepted by the "cold" receiver-converter and redirecting them onto the hot receiver converter, making for greater sensitivity to whatever natural radiation level is available, higher possible temperatures from thermal devices, more affordable equipment to do a given job, and possibly greater productivity from photoelectric devices. It appears evident that placement of additional reflective means within the confines of the concave boundary is more suitable to preassembled collector devices than placement outside the boundary. Limited analytical studies of such additional reflectors have shown them advantageous.
The object of the present invention is to provide a highly efficient, economically competitive solar collector capable of signifigant concentration ratios for possible application to thermal devices and to photoelectric devices and to combination thermal and photoelectric devices.